Characterising plant surfaces for spray adhesion and retention

Abstract

A simple measurement of static contact angle of aqueous acetone droplets on surfaces has been developed for characterising leaf surfaces It allows leaves to be compared and grouped by their surface roughness factor and it differentiates between easy difficult and very difficulttowet species This paper describes how the method has been used to survey a large number of plant species including weeds and crops fruit and foliage High contact angles indicate difficulttowet surfaces The quantitative measure of contact angle is a useful tool to predict spray droplet adhesion and rank plant surfaces for retention properties It can also indicate whether surfactant addition is likely to be beneficial for agrochemical sprays targeted at fruit or foliage on different crops Surfactants were most useful for improving spray droplet adhesion and retention on difficulttowet surfaces but results varied with surface wettability surfactant type and concentration and with plant architecture